Japanese Patent Laying-Open No. 04-295202 discloses an electric motor drive and power processing apparatus used in an electrically powered vehicle. The electric motor drive and power processing apparatus includes a secondary battery, inverters IA and IB, induction motors MA and MB, and a control unit. Induction motors MA and MB respectively include Y-connected windings CA and CB, and to neutral points NA and NB of windings CA and CB, input/output ports are connected through an EMI filter.
Inverters IA and IB are provided corresponding to induction motors MA and MB, respectively, and connected to windings CA and CB, respectively. Inverters IA and IB are connected parallel to the secondary battery.
When the electric motor drive and power processing apparatus operates in a recharging mode, an AC power is supplied to neutral points NA and NB of windings CA and CB, from a single phase power source connected to the input/output port through the EMI filter, and inverters IA and IB convert the AC power supplied to the neutral points NA and NB to a DC power and charge the DC power source.
In the electric motor drive and power processing apparatus, however, in order to realize a controlled battery charge with power factor of 1, single phase power source available for charging the battery is limited. Specifically, the peak voltage (crest value) of the single phase power source for charging the battery must not exceed the battery voltage, and if the voltage crest value of single phase power source should exceed the battery voltage, it becomes impossible to control the power flow and power factor as requested, in the electric motor drive and power processing apparatus described above.